Microstructural characterization of cerium rich phases in new polycrystalline Co–Al–W-xCe superalloys

Abstract

Cerium (Ce) plays an important role in enhancing the properties of Ni and Co-based alloys at high temperatures. However, its influence on the crystallization, microstructure, and properties of Co superalloys is not fully known. This work investigated the effect of Ce-doping on the as-cast microstructure of γ′-formed Co–Al–W alloys. Co–9Al–9W-xCe alloys (x = 0, 0.1, and 0.5) were synthesized and their microstructures were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). Al occupied interdendritic spaces and formed Th2Zn17-type structures. Introduction of Ce to Co–Al based alloys formed Ce-rich interdendritic precipitates, which do not dissolve upon heat treatment.

Keywords

• Co–Ce
• Rare earth elements
• CeCo5
• Ce2Co17
• γ–γ′ cobalt-based superalloys
• Superalloys